Abstract: A fluid handling device to assist in the mixing or separation of two or more fluids utilizing a stack of two types of alternating plates. A first plate has an aperture; a second plate has peripheral spaces around which the fluids may flow. Both types of plates are provided with a plurality of projections that serve to space the plates apart and to provide additional turbulence to the fluids as they flow around the projections. The fluids are forced to proceed back and forth through the alternating plates. The plates may be designed to fit within a housing of circular or polygonal cross-section. The projections may be tapered or non-tapered. The projections may be circular or polygonal in cross-section. Further the heights of the projections may vary to adjust the separation between adjacent pairs of plates to obtain the appropriate degree of turbulence for optimum mixing or separation of the fluids.